4BT Cummins Diesel

3.9L Cummins 4BT Specs, History, & Information

The Cummins 4BT is essentially a 5.9L 12v Cummins minus two cylinders. This 3.9L, 4 cylinder, inline diesel was commonly used in commercial van applications (popular application for Chevy Step Vans - think bread delivery trucks), as well as a variety of construction and agricultural equipment. Generous amounts of torque in a small package make the 4bt common for engine swaps in Jeeps & small trucks/SUVs. In fact, one might argue that the 4BT is the most popular and desirable engine for such swaps as parts and resources are widely available.

The 4BT is dimensionally similar to the 6BT, save for a much shorter length. The pistons, injectors, connecting rods, and valvetrain design are straight off of the 12v Cummins (6BT). Because inline 4 cylinders are not inherently balanced like inline 6 cylinder engines, the engine is noticeably "harsher" than its larger brother and does not build power as "smoothly". The engines can be found in applications with up to a 16,000 lb GVWR, which should serve as a limit for anyone whom plans to use the engine in a custom application.

4BT Cummins Specs

Configuration:

Inline 4 cylinder

Displacement:

3.9 liters, 239 cubic inches

Bore x Stroke:

4.02" x 4.72"

Cylinder Head Material:

Cast iron

Engine Block Material:

Cast iron

Firing Order:

1-3-4-2

Compression Ratio:

17.5 : 1

Injection:

Direct injection, mechanical injection pump

Aspiration:

Turbocharged, non-intercooled

Valvetrain:

OHV, 2 valves per cylinder

Weight:

745 - 782 lbs w/ oil

Oil Capacity:

10 quarts

Governed Speed:

Varies with application

Horsepower:

105 hp @ 2,300 rpm*

Torque:

265 lb-ft @ 1,600 rpm*

Engine Dimensions:

Length:

30.6"

Width:

24.6"

Height:

37.7"

* Common rating, output may vary considerably with application.